 
 (defn check-spec [spec]
 	{:pre [(not (nil? spec))
-				 (re-seq #"^[A-Za-z]$" (clojure.string/trim spec))]}
+				 (re-seq #"^[A-Za-z]$" (trim spec))]}
 		true)
 
 (defn -main

	(let [row-number (first row-instructions)
				letter (second row-instructions)
				row-letter (nth (letter-range \A (ucase-letter letter)) (- row-number 1))]
			(clojure.string/replace row-template (re-pattern (str "[^" row-letter "]")) " ")
	))

(defn diamond [letter]

(ns alphabet-diamond.core
	(:require [clojure.string :as str :refer [upper-case trim]]))

(def ^:const row-template "ZYXWVUTSRQPONMLKJIHGFEDCBABCDEFGHIJKLMNOPQRSTUVWXYZ")

(defn- ucase-letter [letter]
	(int (.charAt (upper-case letter) 0)))

(defn- letter-range [start-letter end-letter]
  (map char (range (int start-letter) (inc (int end-letter)))))
